An example of a known waterproof electrical connector can be found in Japanese Patent Publication No. 95-326422. The waterproof electrical connector according to this publication has an integral rubber waterproof sealing means that is secured on a housing and is disposed at a mating side of the housing and at a side of the housing accommodating a bundle of electrical wires thereby providing a watertight seal for the bundle of wires. The rubber waterproof sealing means is applied from a back side of the housing, that is from the side accommodating the leads, and it is secured in position by a cap member. The rubber waterproof sealing means exerts a watertight connection when a mating housing of a mating connector is engaged with the connector housing, and its housing forms a waterproof coupling therebetween.
Connectors of this type must offer good waterproof properties in order to increase the reliability of the electrical connection. However, the measures aimed at the improvements of waterproof properties create trouble when the mating housings of the connector are coupled together. The reason for this is that in connectors with superior waterproof properties, when the mating housings of the connector are coupled together, air is locked in the space between the mating housings, and since there is no escape for the air, it remains inside the connector at a rather high pressure.
Therefore, the purpose of the present invention is to provide a waterproof electrical connector, the design of which makes it possible to reduce pressure of the air trapped between the mating housings of the mating connectors.